ranget (pronounced rang-et or range-et (I say the latter) or ran-jay if you're Frenchish, I suppose) is a CLI tool that fetches the --url-specified file over HTTP/S using the HTTP RANGE spec to download --size chunks of the file asynchonously using the --max number of workers. When not --debugging, there is a nice progress bar that also calculates the throughput of the workers. If the requested server does not support ranged requests, the file is downloaded "normally".
ranget is an example driver for rangetripper which you can use directly.
--debug Enable debugging output (disables progress bar)
--max int Maximum number of simultaneous downloaders (default 10)
--out string Where to write it it (default "./afile")
--size string Size of chunks to download (whole-numbers with suffixes of B,KB,MB,GB,PB) (default "10MB")
--timeout duration Set a general timeout for the download (default 1m0s)
--trash Delete the file after downloading (e.g. if benchmarking, etc.)
--url string What to fetch